Pseudoscaphirhynchus kaufmanni
Pseudoscaphirhynchus kaufmanni (''Amu Darya sturgeon)' Kingdom: '''Animalia Phylum: Chordata Class: Actinopterygii Order: Acipenseriformes Family: Acipenseridae Genus: Pseudoscaphirhynchus Species: Pseudoscaphirhynchus kaufmanni Environment: milieu, climate zone, depth range, distribution range: Freshwater; brackish; demersal; potamodromous; depth range 1 - 2 m. Temperate; 10°C - 20°C. Distribution: Asia: Former USSR: Amu Darya River from the Pyandzh to the mouths and lower tributaries. Sometimes in the brackish water of Taldyk Bay, the delta of the Amu Darya in the Aral Sea. Considered close to extinction. International trade restricted (CITES II, since 1.4.98; CMS Appendix II). Registered in the 1984 USSR Red Book; 1985 Turkmen SSR Red Data Book; 1996 IUCN Red List; an d1997 CITES Lists. Size, weight, age: Max. length: 75 cm; weight: 2 kg; age: ?''' ''Short description:'' The Amu Darya sturgeon is a small sturgeon, but the largest species of Pseudoscaphirhynchus, reaching up to 2 kg (4.4 lb) in weight and 75 cm (30 in) in total length, excluding tail filament. It has a long, thin tail filament. For example, two individuals that both had a length of about 55 cm (22 in) excluding tail filament were 77 cm (30.5 in) and 85.5 cm (33.5 in) including tail filament. The species occurs in two morphs: a relatively large, light-coloured and late maturing morph, and a small, dark-coloured and early maturing morph. The small morph is roughly of similar size to P. hermanni, a species that lacks a tail filament. ''Biology:'' Its natural habitat and population have declined due to the breakage of the hydrological regime of the Amu Dariya River. Usual weight not more than 600-700 grams. Females with mature hard roe, very rare. Apparently sensitive to oxygen content in the water, changes in its chemical content, and to pollution. Fishing is prohibited. Spawns at 16° C. ''Life cycle and mating behavior:'' The Amu Darya sturgeon feeds on small fish and aquatic insect larvae, with large individuals being mostly piscivorous. Studies in the 1960s and 1970s showed that Amu Darya sturgeon reach maturity when 5–8 years old (slightly later in females than males), but in the 1990s the youngest mature individuals only were 4 years old, possibly due to environmental changes in their habitat. The breeding season is from March to May when the water is 14 to 16 °C (57 to 61 °F). During a season, a female of the large morph lays about 3,100–36,500 eggs and a female of the small morph about 1,000–2,000 eggs, but it is possible that they only do this every 4–5 year. The species can reach an age of more than 14 years. Historically, it was known to hybridize with P. hermanni, with the offspring having features that are intermediate between the two species. ''Main reference:'' '''Berg, L.S., 1962. Freshwater fishes of the U.S.S.R. and adjacent countries. volume 1, 4th edition. Israel Program for Scientific Translations Ltd, Jerusalem. (Russian version published 1948). IUCN Red List Status: CRITICALLY ENDANGERED (''CR)' '''CITES: Appendix II: International trade monitored CMS: Appendix II: Migratory species conserved through agreements Threat to humans: Harmless Human uses: Fisheries: commercial. Category:Acipenseridae, Sturgeons